B'nos Moav. Arayos and Avoda Zara

Bilam advised the king of Midian to do something that would bring Hashem's anger upon Klal Yisrael.  It worked, and it brought about a disaster.  A plague broke out among the Jews, and the judges were told to take up their swords and slay those that had sinned.  According to Rashi, they actually went and killed people, and the numbers are beyond belief (two each for every judge,so Rashi says they killed something like one hundred sixty thousand men, out of six hundred thousand- more than one quarter of the Jewish men.  The Ramban finds the numbers so extreme that he says that because of Pinchas' intervention, the gzeira for the judges to kill was nullified.)  As terrible as it was, it would have been far worse if not for Pinchas' intervention.

וישב ישראל בשטים ויחל העם לזנות אל בנות מואב.  ותקראן לעם לזבחי אלהיהן ויאכל העם וישתחוו לאלהיהן.  ויצמד ישראל לבעל פעור ויחר אף ה בישראל.  ויאמר ה אל משה קח את כל ראשי העם והוקע אותם לה נגד השמש וישב חרון אף ה מישראל.  ויאמר משה אל שפטי ישראל  הרגו איש אנשיו הנצמדים לבעל פעור.   והנה איש מבני ישראל בא ויקרב אל אחיו את המדינית לעיני משה ולעיני כל עדת בני ישראל והמה בכים פתח אהל מועד.  וירא פינחס בן אלעזר בן אהרן הכהן ויקם מתוך העדה ויקח רמח בידו.   ויבא אחר אישישראל אל הקבה וידקר את שניהם את איש ישראל ואת האשה אל קבתה ותעצר המגפה מעל בני ישראל.   ויהיו המתים במגפה ארבעה ועשרים אלף

Pesukim and maamarei Chazal spread over the three parshios seem to give  inconsistent explanations for exactly what sin it was that precipitated the terrible punishment.  Some indicate that it was the Avoda Zara (ויצמדו לבעל פעור), while others talk of the z'nus (אמר להם אלקיהם של אלו שונא זימה הוא).

The achronim bring an interesting mesora.  They say that they have a mesora in the name of the gaon איש מפי איש עד משה רבנו- an amazing expression that we find almost nowhere outside of הלכה למשה מסיני, and certainly never where it involves something found nowhere in Chazal.  The mesora is that every avoda zara has arayos, and arayos is a necessary ingredient in every avoda zara.  According to this, Rav Steinman (Ayeles HaShachar al HaTorah) says, the kashe is not shver.  It is a false dichotomy.  Avoda Zara is Arayos, and Arayos can be Avoda Zara.

הרמ"מ משקלאוו (בס' מים אדירים על האידרא זוטא) כתב שמעתי מהגר"א ז'ל קבלה בידינו מן הגאונים איש מפי איש עד משה רבינו ע'ה שכל עבודה זרה הי' צריך דבר ערוה ולכן כתיב אצל כל ע'ז ויזנו אחרי הבעלים וקם העם הזה וזנה עכ'ל

In the Hebrewbooks copy the sefer is not called Mayim Adirim, it's called מנחם ציון.  (For those of you that never heard of the Idra Zuta, or even the Idra Rabba, it is from the Zohar in Haazinu, describing the passing of Rav Shimon bar Yochai.  Wiki articles in Hebrew and English.  For an explanation of why it has two different names, Mayim Adirim and Menachem Tzion, I direct your attention to the handwritten note on page two of the Menachem Tzion at hebrewbooks.org)

The language of the Gaon's talmid Reb Menachem Mendel in his sefer is even more clear- that arayos is not only a tool of avoda zara, but a part of its essential character.  I don't understand the discussion that leads up to this point, but he says that the reason arayos is not mentioned among the things that are makchish famaliah shel maalah is because arayos is included in Avoda Zara:

...........
והמדבר זה הוא קוצץ בנטיעוח שמפריד בין נגל׳ לנעלם והמה מהפכין ממטה לנחש ואם נותנין אות ומופת לדבריהם אזי גם האות והמופת מן המכחישים פמליא ש״מ והן עע״ז וש"ד וג׳׳ע ממש ומה דלא חשיב ג״ע נמי שא״צ כי שמעתי מאדמו״ר הגאון ז״ל שכך קבלה בידינו מהגאונים איש מפי איש עד מרע״ה שכל ע״ז צריך עבודת דבר ערוה ולכן כ' אצל ויזנו אחרי הבעלי׳ וקם העם הזה וזנה

We don't need historical support for this, but when I said it over on Shabbos, our professor of classics, Rabbi Dr. Yitzchak Resnik, said that this is well known to be the case in the classic era.  There were temples where the priestesses were mukdash to have relations with supplicants, through which a state of "holy" ecstasy would be attained.  We all are familiar with the erotic carvings associated with Hinduism as well.

Rav Schwab (in his Maayan Beis HaShoeiva) says something that relates to this.  He asks, how can it be that such a great man as Zimri could do such a disgusting thing.  Besides the fact that he was quite elderly, if you're reading this you know what a great man he must have been to be a nasi of a Shevet in Klal Yisrael, and he did something that even a prosteh person would not do, and davka with a shiksa, knowing full well what consequences he was risking.  Rav Schwab answers that the Gemara (San 63b) says

אמר רב יהודה אמר רב יודעין היו ישראל בעבודת כוכבים שאין בה ממש ולא עבדו עבודה זרה אלא להתיר להם עריות בפרהסיא

Rav Schwab says that Zimri saw that many Jews were inflamed with lust for the Moaviyos and it was that lust that drove them to do Avoda Zara, because their consciences would not let them sin.  The idea of this kind of hefkeirus of arayos was so horrible, it was so shameful, that they simply could not do the aveira.  It was only by saying to themselves that they now are worshippers of Pe'or, and zenus is the right and "holy" thing to do, that their conscience stopped bothering them!  It's not shameful, it's not horrible, it's not hefkeirus, it's our way of worshipping our god!.  They used the excuse of becoming ovdei avoda zara to kasher their irresistible taiva for zenus.  So Zimri decided that the best eitza is to remove the extreme stigma of ze'nus; to show people that even a holy and great man can give in to his desires.  Once the people would see this, then they would be willing to consort with the Moavi and Midani women without having to drop Yiddishkeit entirely.  Thus, although they would be punished for zenus with goyim, it would be a far smaller sin than Avoda Zara.  Rav Schwab says that Zimri was wrong because the sin of publicly consorting with Moaviyos and Midianos was terrible as well, and you don't solve the worse problem of avoda zara by being mattir a lesser but also terrible sin of arayos.

With the Gaon, we can enhance Rav Schwab's teretz.  Zimri's error was thinking that Arayos and Avoda Zara can be separated. But that is not true.  Arayos is a av melacha in the parsha of avoda zara; and lav davka avoda zara,- it can be minus or kefira, too, which are also in the parsha of avoda zara.  Zenus and arayos are inseparable from avoda zara.  Zimri thought it was worth it to cut off the leg to save the body.   If they don't feel so guilty about zenus, at least they won't need to throw away Yiddishkeit and adopt avoda zara to rationalize their zenus.  What he didn't realize was that he was inflaming the disease, not eliminating it.  Allowing zenus is not only a sin because of the inherent aveira of zenus, but also because it ultimately brings a person to avoda zara.

Update: Thank  you Reb Chaim B for bolstering the point with the Gemara in Sanhedrin 81b and with slight changes the Rambam 12 I'B 6:

הבועל ארמית קנאין פוגעין בו, בעא מיניה רב כהנא מרב, לא פגעו בו קנאין מהו, אינשיה רב לגמריה, אקריוהו לרב כהנא בחלמיה בגדה יהודה ותועבה נעשתה בישראל ובירושלים, כי חלל יהודה קדש ה' אשר אהב ובעל בת אל נכר, אתא אמר ליה הכי אקריון, אדכריה לרב לגמריה, בגדה יהודה זו עבודת כוכבים, וכן הוא אומר בגדתם בי בית ישראל נאום ה', ותועבה נעשתה בישראל ובירושלים זה משכב זכור... כי חלל יהודה קדש ה' זו זונה, וכן הוא אומר לא יהיה קדש, ובעל בת אל נכר זה הבא על הכותית, וכתיב בתריה יכרת ה' לאיש אשר יעשנה ער ועונה מאלקי יעקב ומגיש מנחה לה' צב-אות, אם תלמיד חכם הוא, לא יהיה לו ער בחכמים ועונה בתלמידים, אם כהן הוא לא יהיה לו בן מגיש מנחה לה' צב-אות. אמר רבי חייא בר אבויה כל הבא על הכותית כאילו מתחתן בעבודת כוכבים, כדכתיב ובעל בת אל נכר, וכי בת יש לו לאל נכר, אלא זה הבא על הכותית

The only comment I would make is that כאילו מתחתן בעבודת כוכבים is talking about specifically a kusis, in that the passuk being interpreted uses the words בת אל נכר, while the Gaon, I think, is talking about Arayos in general- צריך עבודת דבר ערוה.

But there is a Chazal brought in two places by Rabbeinu Bachaye that does relate all to Avoda Zara:  It is in his peirush on Chumash towards the beginning of Kedoshim and in his Kad Hakemach.  It says

 כל המסתכל באשה (בפני אשה) עובר משום אל תפנו אל האלילים

Still, it's not exactly what the Gaon says.  With a Chazal or not, the Gaon stands on its own merits- it's a mesora from the Geonim all the way to Moshe Rabbeinu.